Breast feeding is the preferred method of feeding human infants, providing both energy and essential nutrients for the developing baby. As far as energy supply is concerned, fat is by far the most important constituent of milk. The fat also contains essential fatty acids (EFAs), vitamin-like essential nutrients which are extremely important in many aspects of human structure and function. EFAs seem to be particularly important for the developing brain, immunological system and cardiovascular system although they have roles to play in every organ in the body.
During prolonged breast feeding, the total fat and the EFA contents of human milk tend to fall progressively. These falls may limit the success of breast feeding and lead to an early requirement for supplementation with other foods. We have now discovered a method of reducing or preventing the fall of breast milk fat levels during prolonged breast feeding and of in many cases actually increasing both the total fat and the EFA content of human milk.
The outline of n-6 series fatty acid conversion in the body is: ##STR1##
As appears from the chart, linoleic acid (LA) is the main n-6 EFA in the diet but in order to be useful to the body it must be converted first to gamma-linolenic acid (GLA) and then to further metabolites such as dihomo-gamma-linolenic acid (DGLA) and arachidonic acid (AA) which are precursors of 1 and 2 series prostaglandins respectively. GLA is very rapidly converted to DGLA and the two may be regarded as metabolically equivalent. However, the formation of GLA itself is slow and rate-limited by the 6-desaturase enzyme acting to generate it from LA. Similarly the conversion of DGLA to AA is also relatively slow.